The Protein Expression Shared Resource provides Cancer Center members expert technical assistance in recombinant DNA plasmid engineering, protein expression in bacteria and baculovirus-infected insect cells, purification of recombinant proteins, and production of high-titer retroviruses (e.g. lentiviruses) for delivery of shRNA and cDNAs to mammalian cells. Cancer Center investigators require high quality recombinant proteins to achieve a wide range of experimental objectives, such as characterization of enzymatic activities, crystallization for structural analysis, characterization of structure-function relationships of protein-protein, protein-nucleic acid, and protein-small molecule interactions; development of assays for small molecule high throughput screening; and immunization of rabbits/mice to generate custom antibodies. The Resource continues to maintain cutting edge technology for recombinant protein expression and preparation of high-titer retroviral vector. Under the guidance of an experienced Managing Director, laboratory staff are highly cross-trained technical experts in all areas of vector technology for recombinant protein expression, baculovirus generation, affinity and conventional chromatography approaches to protein purification, and production of infectious retroviruses. The centralization and standardization of these practices allows for high throughput expression plasmid construction and large-volume protein expression services, including quality assurance and control procedures to ensure efficient, consistent production and purification of high quality recombinant proteins. The Resource also maximizes biosafety by confining retroviruses (e.g. lentivirus) production to a centralized biosafety level 2 (BSL2) unit, which prevents aerosolization of viruses from contaminating incubators and parental cultures of cell lines, and improves quality control in the production of virus stocks to be used in gain- and loss-of-function experiments in vitro and in vivo. Protein Expression was classified as a Type I Shared Resource to reflect the well-defined, essential nature of its services. This group classification is described in the Cancer Center Administration section of this application. In the last funding period the Cancer Center continued to invest in maintaining a state-of-the-art Resource. Protein Expression Shared Resource plays a crucial role in providing preliminary data to support project development, publications, and grant applications for members of all three Cancer Center Programs.